2,580 research outputs found

    Form-focused instruction to identify category of clauses: the case of Lebanese university students of ESL

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    Un área de gramática que desafía a los estudiantes universitarios de primer año de inglés como segundo idioma ESL en la Universidad Libanesa es las oraciones. En una clase de instrucción centrada en la forma, los estudiantes de ESL suelen hacer bien en la construcción de oraciones adjetivas, y de alguna manera en las oraciones de adverbio, así, sin embargo, se enfrentan a dificultades en la construcción de oraciones nominales. Otro desafío mayor aparece cuando se pide a los estudiantes que identifiquen el tipo de la oración, especialmente cuando se usa el mismo pronombre relativo, como “cuándo” o “dónde”, para construir los tres tipos de oraciones: adjetivo, adverbio y sustantivo. Siguiendo el enfoque cuasi-experimental cuantitativo, a través de un pre y un post-test, el presente estudio investigó estos desafíos con ilustraciones del trabajo de los estudiantes, que hace el corpus de este estudio, y proporciona un análisis lingüístico cognitivo y análisis meta-cognitivo, para resolver este problema. Prosigue con la exploración de técnicas de enseñanza basadas en las características lingüísticas idiosincrásicas de cada tipo, en un intento de capacitar a los estudiantes para diferenciar entre los tres tipos.One area of grammar that challenges first year university learners of English as a second language ESL at the Lebanese university is clauses. In a form-focused- instruction class, ESL learners usually do well on constructing adjective clauses and somehow on adverb clauses as well, yet they face difficulty in constructing noun clauses. Another greater challenge appears when learners are asked to identify the type of the clause especially when the same relative pronoun, such as “where” or “when”, is used in constructing the three types of clauses, namely adjective, adverb and noun. Following the quasi-experimental quantitative approach, via a pre- and a post-test, the present study investigated these challenges with illustrations of students’ work, which makes the corpus of this study, and provides a linguistics analysis, cognitive and meta-cognitive analysis, to solve this problem. It proceeds with exploring teaching techniques based on the idiosyncratic linguistic feature of each type in an attempt to enable learners to differentiate between the three types of clauses

    Black holes in N=2 supergravity theories and harmonic functions

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    We present dyonic BPS static black hole solutions for general d=4, N=2 supergravity theories coupled to vector and hypermultiplets. These solutions are generalisations of the spherically symmetric Majumdar-Papapetrou black hole solutions of Einstein-Maxwell gravity and are completely characterised by a set of constrained harmonic functions. In terms of the underlying special geometry, these harmonic functions are identified with the imaginary part of the holomorphic sections defining the special K\"ahler manifold and the metric is expressed in terms of the symplectic invariant K\"ahler potential. The relations of the holomorphic sections to the harmonic functions constitute the generalised stabilisation equations for the moduli fields. In addition to asymptotic flatness, the harmonic functions are also constrained by the requirement that the K\"ahler connection of the underlying Hodge-K\"ahler manifold has to vanish in order to obtain static solutions. The behaviour of these solutions near the horizon is also explained.Comment: 20 pages, LaTeX, an important reference is adde

    Special Geometry and Space-time Signature

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    We construct N=2 four and five-dimensional supergravity theories coupled to vector multiplets in various space-time signatures (t,s), where t and s refer, respectively, to the number of time and spatial dimensions. The five-dimensional supergravity theories, t+s=5, are constructed by investigating the integrability conditions arising from Killing spinor equations. The five-dimensional supergravity theories can also be obtained by reducing Hull's eleven-dimensional supergravities on a Calabi-Yau threefold. The dimensional reductions of the five-dimensional supergravities on space and time-like circles produce N=2 four-dimensional supergravity theories with signatures (t-1,s) and (t,s-1) exhibiting projective special (para)-K\"ahler geometry.Comment: 13 page

    Classical Entropy of N=2 Black Holes: The minimal coupling case

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    We discuss the entropy and the transformation properties of classical extremal N=2 black hole solutions in supergravity theories associated with the minimal coupling models CP(n-1,1). The entropy is given by a manifestly invariant quantity under the embedding of the duality group SU(1,n) into Sp(2n+2) which is a symmetry of the classical BPS mass formula.Comment: 8 pages, Late

    Phantom Metrics With Killing Spinors

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    We study metric solutions of Einstein-anti-Maxwell theory admitting Killing spinors. The analogue of the IWP metric which admits a space-like Killing vector is found and is expressed in terms of a complex function satisfying the wave equation in flat (2+1)-dimensional space-time. As examples, electric and magnetic Kasner spaces are constructed by allowing the solution to depend only on the time coordinate. Euclidean solutions are also presented.Comment: 13 page
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